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Merge pull request #33 from eswartz/pr-pnmimage-premultiply

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Add PNMImage premultiply/unpremultiply methods.
This commit is contained in:
rdb 2015-06-01 15:25:55 +01:00
commit a73b5b3fd1
2 changed files with 60 additions and 0 deletions
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57
panda/src/pnmimage/pnmImage.cxx
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@ -622,6 +622,63 @@ make_grayscale(float rc, float gc, float bc) {
setup_rc();
}
////////////////////////////////////////////////////////////////////
// Function: PNMImage::premultiply_alpha
// Access: Published
// Description: Converts an image in-place to its "premultiplied"
// form, where, for every pixel in the image, the
// red, green, and blue components are multiplied by
// that pixel's alpha value.
//
// This does not modify any alpha values.
////////////////////////////////////////////////////////////////////
void PNMImage::
premultiply_alpha() {
if (!has_alpha()) {
return;
}
for (int y = 0; y < get_y_size(); y++) {
for (int x = 0; x < get_x_size(); x++) {
float alpha = get_alpha(x, y);
float r = get_red(x, y) * alpha;
float g = get_green(x, y) * alpha;
float b = get_blue(x, y) * alpha;
set_xel(x, y, r, g, b);
}
}
}
////////////////////////////////////////////////////////////////////
// Function: PNMImage::unpremultiply_alpha
// Access: Published
// Description: Converts an image in-place to its "straight alpha"
// form (presumably from a "premultiplied" form),
// where, for every pixel in the image, the red,
// green, and blue components are divided by that
// pixel's alpha value.
//
// This does not modify any alpha values.
////////////////////////////////////////////////////////////////////
void PNMImage::
unpremultiply_alpha() {
if (!has_alpha()) {
return;
}
for (int y = 0; y < get_y_size(); y++) {
for (int x = 0; x < get_x_size(); x++) {
float alpha = get_alpha(x, y);
if (alpha > 0) {
float r = get_red(x, y) / alpha;
float g = get_green(x, y) / alpha;
float b = get_blue(x, y) / alpha;
set_xel(x, y, r, g, b);
}
}
}
}
////////////////////////////////////////////////////////////////////
// Function: PNMImage::reverse_rows
// Access: Published

3
panda/src/pnmimage/pnmImage.h
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@ -133,6 +133,9 @@ PUBLISHED:
void make_grayscale(float rc, float gc, float bc);
INLINE void make_rgb();
void premultiply_alpha();
void unpremultiply_alpha();
BLOCKING void reverse_rows();
BLOCKING void flip(bool flip_x, bool flip_y, bool transpose);